Validation of a grading system for the attachment of the superior turbinate to the sphenoid face.

BACKGROUND: The attachment of the superior turbinate to the sphenoid face may be an important factor in determining the approach for sphenoidotomy. We sought to validate a previously described 4-type grading system for superior turbinate attachment (Type: A, within its medial one-third; B, in its middle one-third; C, to its lateral one-third; and D, directly to the orbit) to the face of the sphenoid sinus and to make recommendations for its use in determining the method of sphenoidotomy (transethmoidal vs transsphenoethmoidal).

METHODS: Single-slice images through both sphenoid sinus ostia were obtained from axial series of computed tomography (CT) scans. Eighteen (36 ostia) sets of scans were used. Attachment type (A-D) in each image was classified by 10 experienced sinus surgeons and compared against a "gold standard" grading performed by the senior author (A.J.), who was the developer of the grading system.

RESULTS: Mean accuracy was 63% (95% confidence interval [CI], 54%-72%) for the 4-type grading system. When Types A+B and Types C+D were grouped together, mean accuracy was 91% (95% CI, 84%-97%). For the 2-group classification system, bootstrap analysis suggested that 97% of physicians attain an accuracy of at least 80%.

CONCLUSION: Accuracy using the 4-type classification is too low to be practically useful. Accuracy using the 2-group system may be sufficiently high to be a useful aid in selecting a surgical approach. We recommend a transethmoid sphenoidotomy for Types A and B and a transsphenoethmoidal approach to the sphenoid for Types C and D.